External vacuum expander with non-adhesive rim

Abstract

A tissue expander having a shell, an opening in the shell in communication with an external vacuum source to apply a vacuum within the shell and impart a distracting force to expand tissue, and a rim connected to the shell and adapted to be in contact with a skin of a patient. The rim is non-fixedly attached to the skin of the patient and moves laterally outwardly with respect to the shell under application of the vacuum.

What is claimed is: 
     
       1. A tissue expander wearable by a patient comprising a shell, an opening in the shell for an externally extending tube in communication with an external vacuum source to apply a vacuum within the shell and the shell configured to impart a distracting force to expand tissue into the shell, and a rim connected to the shell and adapted to be in contact with a skin of a patient, wherein the rim is asymmetric and has a narrower skirt medially and a more curved inward skirt laterally to provide a lateral side with deeper concavity and a length longer than a medial side, the rim has a low friction non-anchored contact surface configured to recruit peripheral skin and dissipate the shear forces and is non-fixedly attached to the skin of the patient during wearing by the patient and is configured to slide laterally outwardly with respect to the shell under application of the vacuum as the rim increasingly spreads under increasing pressure to increase a surface contact area and decrease skin counter pressure as the tissue expander applies a downward force against the skin. 
     
     
       2. The tissue expander of  claim 1 , wherein the rim is composed of synthetic rubber and has a lubricating layer on a bottom surface to glide over the skin, thereby reducing shear stress between the rim and contact surface of the skin. 
     
     
       3. The tissue expander of  claim 1 , wherein the rim has a smooth, uninterrupted non-adherent, non-adhesive lower tissue contact surface. 
     
     
       4. The tissue expander of  claim 1 , wherein the rim has a concave tapered portion forming a concavity that forms the skirt that deflects to open and spreads out laterally, the concavity directed toward the tissue. 
     
     
       5. The tissue expander of  claim 1 , wherein the rim is configured such that when downward pressure is applied by the vacuum, a lower tissue engaging surface of the rim conforms to the contour of a body of the patient and deflects to increase a surface in contact with the skin and prevent an increase in counter pressure against the skin. 
     
     
       6. The tissue expander of  claim 1 , wherein the rim has a feathered down periphery to wrap around a portion of a body of the patient and grip a torso of the patient. 
     
     
       7. The tissue expander of  claim 1 , wherein the rim has a malleable edge thinner than an inner portion of the rim, the edge being more deflectable than the inner portion. 
     
     
       8. The tissue expander of  claim 1 , wherein the skirt is configured such that when downward pressure is applied, a downward force from the shell is counteracted by the skin and the rim can stretch out from a concave to a convex or near flat configuration at its highest pressure point while remaining concave at a lateral peripheral edge, and is configured such that a counterforce between the skirt and tissue is evenly distributed over a contact area of the skin to avoid pressure points with increasing pressures. 
     
     
       9. The tissue expander of  claim 1 , wherein the rim further comprises a pocket configured for receipt of a fin. 
     
     
       10. The tissue expander of  claim 1 , wherein the shell is removably connectable to the rim for connection of shells of varying size. 
     
     
       11. The tissue expander of  claim 1 , wherein as vacuum pressure increases surface contact area of the rim increases. 
     
     
       12. A tissue expander comprising a shell, an opening in the shell in communication with an external vacuum source to apply a vacuum within the shell and the shell configured to impart a distracting force to expand tissue and a rim connected to the shell and adapted to be in contact with a skin of a patient, wherein the rim is asymmetric and has a narrower skirt medially and a more curved inward skirt laterally to provide a lateral side with deeper concavity and a length longer than a medial side, the rim has a non-adhesive concave lower surface in a first initial pre-vacuum condition wherein peripheral edges camber inwardly, and at least a segment of the concave lower surface has a second vacuum induced condition upon the application of vacuum wherein it has a convex surface upon application of vacuum, the rim configured to deform to invert from the concave surface to the convex surface, the rim having a tapering edge in the first and second conditions. 
     
     
       13. The tissue expander of  claim 12 , wherein a periphery of the rim on a lateral side remains concave in the vacuum induced condition to preserve a seal. 
     
     
       14. The tissue expander of  claim 13 , wherein the rim is configured to change angle from a more vertical to a more horizontal with application of pressure as downward pressure is applied, and the rim is configured such that a counterforce between the rim and skin is evenly distributed over a skin contact area. 
     
     
       15. The tissue expander of  claim 12 , wherein the rim tapers down to a feathered edge. 
     
     
       16. The tissue expander of  claim 12 , wherein the rim is composed of a low durometer rubber material. 
     
     
       17. A tissue expander comprising a shell, an opening in the shell for an externally extending tube in communication with an external vacuum source to apply a vacuum within the shell, the shell configured to impart a distracting force to expand tissue into the shell and a rim connected to the shell and adapted to be in contact with a skin of a patient, wherein the rim is asymmetric and has a narrower skirt medially and a more curved inward skirt laterally to provide a lateral side with deeper concavity and a length longer than a medial side, and the rim has a feathered edge to increase contact area with the skin, the rim configured to spread to increase contact with tissue as downward force increases during application of the distracting force to expand tissue within the shell, the shell being of a material more rigid than the rim.